Hammocks provide a surface suspended between upright structures (e.g. trees, posts, etc.) on which a person may lie suspended above the ground. Hammocks are typically constructed of a sheet of material, often flexible (e.g. canvas, netting, ropes, etc.) gathered at the ends and suspended from upright structures by ropes, straps or like means.
One drawback of traditional hammocks is known as hammock sag, whereby the middle of the hammock sags below the ends creating a curved supporting surface. Such a surface is uncomfortable for an occupant as it does not follow the natural profile that the person's body will take when lying down. Furthermore, traditional hammocks provide no lumbar support or support under the knees and they are unstable and prone to tipping.
There have been a number of attempts to provide so-called self-leveling hammocks in an effort to ameliorate the problem. For example, Brazilian hammocks provide an extra wide sleeping surface so that a person may lie diagonally. Such hammocks require extra material and an occupant must be careful not to move into a non-diagonal position. U.S. Pat. No. 6,701,549, U.S. Pat. No. 645,805, U.S. Pat. No. 249,403, U.S. Pat. No. 202,814, U.S. 2002/0042951 and U.S. 2004/0006820 all describe various ways of compensating for hammock sag. None of these has been wholly successful at providing a comfortable, stable sleeping surface in a portable, easy to set-up hammock.